This is a list of computer file formats, organized by type. Filename extensions are usually noted in parentheses if they differ from the format name or abbreviation. Many operating systems do not limit filenames to a single extension shorter than 4 characters, as was common with some operating systems that supported the FAT file system. Examples of operating systems that do not impose this limit include Unix-like systems. Also, Microsoft WindowsNT, 95, 98, and Me do not have a three character limit on extensions for 32-bit or 64-bit applications on file systems other than pre-Windows 95/Windows NT 3.5 versions of the FAT file system. Some filenames are given extensions longer than three characters.

3DT — 3D Topicscape The database in which the meta-data of a 3D Topicscape is held. A 3D Topicscape is a form of 3D concept map (like a 3D mind-map) used to organize ideas, information and computer files.

ATY — 3D Topicscape file, produced when an association type is exported by 3D Topicscape. Used to permit round-trip (export Topicscape, change files and folders as desired, re-import them to 3D Topicscape).

FES — 3D Topicscape file, produced when a fileless occurrence in 3D Topicscape is exported to Windows. Used to permit round-trip (export Topicscape, change files and folders as desired, re-import them to 3D Topicscape).

TPC — 3D Topicscape file, produced when an inter-Topicscape topic link file is exported to Windows. Used to permit round-trip (export Topicscape, change files and folders as desired, re-import them to 3D Topicscape).

List of the most common filename extensions used when a game's ROM image or storage medium is copied from an original ROM device to an external memory such as hard disk for back up purposes or for making the game playable with an emulator. In the case of cartridge-based software, if the platform specific extension is not used then filename extensions ".rom" or ".bin" are usually used to clarify that the file contains a copy of a content of a ROM. ROM, disk or tape images usually do not consist of a single file or ROM, rather an entire file or ROM structure contained within a single file on the backup medium.[14]

These file formats are fairly well defined by long-term use or a general standard, but the content of each file is often highly specific to particular software or has been extended by further standards for specific uses.